Recently, in a field of medical instruments, micro machines, etc., a need for small-size and lightweight sensors and transducers which transform a certain kind of energy into another one is increasing. In addition, in a field of industrial robots, personal robots, etc., a need for lightweight and flexible transducers is also increasing.
As described above, polymer transducers are attracting attention in various fields, as they are lightweight and flexible. Various polymer transducers have been reported.
For example, Patent Document 1 described below, discloses a small-sized and flexible actuator device comprising: a cation exchange film, and electrodes each is attached to a respective surface of the ion exchange film. In Patent Document 2, the present inventors disclose a polymer transducer having an excellent flexibility formed from a solid polymer electrolyte component having a specific molecular structure. The inventions described in both Patent Documents 1 and 2 have a structure in which at least a pair of electrode layers is provided with respect to a solid polymer electrolyte. The inventions have a lamination structure in which the electrode layer is formed on a solid polymer electrolyte using electroless plating technique.
In Patent Documents 3 and 4, a polymer transducer is disclosed, which has an electrode layer comprising a solid polymer electrolyte and conductive fine particles. In operation of the polymer transducer, formation of an electric double layer plays an important role at an interface between the solid polymer electrolyte and a conductive substance such as dendritic metal formed by electroless plating method, metal fine particles, carbon fine particles, etc. In order to form more electric double layers, methods for forming them with such compositions have been adopted.
Electroless plating methods are generally carried out by repeating several times of noble-metal doping and reduction by a reducing agent, being unsuitable for industrial production. However, Patent Documents 3 and 4 and non-Patent Documents 1 to 3, disclose a composition comprising a solid polymer electrolyte and conductive fine particles those of which are dissolved or dispersed in an appropriate media to obtain a liquid or a paste. From the obtained liquid or paste, an electrode film is formed. These processes are expected to be industrially and economically feasible.
In a case where a polymer transducer is produced using this paste and printing techniques, the electrode film should be formed to have a certain film thickness so as to form more electric double layers. As for an electrolyte film, a certain film thickness is required to surely and electronically insulate the opposing electrode films from each other. A desired film thickness of these electrode film and electrolyte film can be achieved generally by using a paste with a high solid content concentration and by adopting a multiple repetitions of a coating and drying steps. However, there are such problems as a sharp rise in the viscosity of the paste due to an increase in the solid content concentration, and as an increase in manufacturing costs, etc. As seen above, the conventional pastes have still disadvantages in adjusting the solid content concentration, storage stability, handling ability, coatability, etc. A paste with excellent practicality has been desired.